This invention pertains to a clockspring interconnector for enclosing an electrical conductor cable, the clockspring interconnector electrically connecting a rotatable electric device with a stationary electric device.
An increasing number of automobiles have air bag crash systems. An air bag is typically located on the steering wheel facing the driver. The air bag must be in continuous electrical connection with sensors in the car body. The sensors provide an electrical signal to the air bag crash assembly which instantly inflates the air bag in the event of a crash.
Accordingly, there is a need for an electrical connection between the rotatable potion of the air bag assembly which is mounted to the steering wheel, and the remaining portion of the assembly, which is in a stationary position in the car body. Electrical connections between rotatable and stationary parts are well known. Typically, an electrical brush rests upon a conductive ring, with one of the parts being rotatable to provide such rotatable electrical connection. However, there is a risk, particularly during the impact of an accident, of a transient failure of electrical connection with a brush and ring system, which would result in failure of the entire air bag system crash assembly.
Accordingly, a clockspring interconnector has been previously developed, comprising an outer housing, a rotor member and multiple intermediate housing members for enclosing and connecting the members; the housing and rotor member rotatably associated with one another at a plurality of bearing surfaces. A "clockspring" is located inside the interconnector. The clockspring is a flat conductor cable and has two ends conductively attached to conductor wires which pass out of the interconnector to unite the air bag to the sensing device. The interconnector is mounted on the steering column, and the steering wheel may be rotated in either direction while a continuous, positive electrical connection is provided between air bag sensors via the clockspring interconnector.
While prior art clockspring interconnectors are effective to provide the necessary continuous electrical connection between an air bag or other device on a rotating column and a stationary portion of a circuit, the prior art systems were sometimes wound completely tight before the device was installed making the installed device useless. This problem was partially solved by providing a clockspring assembly with a device that kept the clockspring interconnector from rotating prior to installation.
Such a locking mechanism was described in U.S. Pat. No. 4,722,690. That patent describes a clockspring interconnector which includes a projection which engages a noncircular aperture of the rotor member to prevent the rotor member from rotating. This projection was removable by hand by reaching into the center aperture of the clockspring. This design is disadvantageous in that it requires a center aperture which is noncircular and also requires exposure of the center aperture on the clockspring so that an operator may grasp the projection for removal. In certain assembly operations of the clockspring to the steering wheel and steering column, it is sometimes impossible to remove such a locking projection which may become enclosed by a steering wheel housing or steering column housing. Thus, there is a need for a removable external locking means which may be exposed after assembly of the clockspring with a steering wheel housing and steering column housing. Such prior art locking mechanisms also required an additional locking mechanism to lock the steering column assembly prior to assembly of the clockspring assembly. Such an improved external locking means providing exposure after assembly could also eliminate the extra part for the steering column locking mechanism.
U.S. Pat. No. 5,171,157, describes a clockspring interconnector including spring-loaded locking pegs integral to the internal hub of the rotor. This patent describes locking pegs which may be depressed only upon engagement from above, providing direct vertical force onto the locking pegs. Such a design requires that a column being inserted through the center of such a clockspring have protruding portions which will project perpendicular to the path of insertion of the column into the clockspring and provide surfaces which will engage the locking pegs in a vertical direction. Such a system is disadvantageous because the hub being inserted into such a clockspring must be specially designed so that the protruding portions of the hub engage the locking pegs while still allowing complete mating insertion of the column through the clockspring and with the steering assembly. Accordingly, it is desired to have a locking means which may be engaged without the need of a specially design column.
U.S. Pat. No. 5,059,134, describes a connection location where the electrical conductors of the flat ribbon cable are serially connected to a connection conductor wires via the engagement of the uninsulated end portions of conductor wires against a clamping body which is surrounded by a protective sheath injection molded about the clamping body. This arrangement is both difficult and costly to assemble. In order to position the clamping body against the conductor wires and then injection mold the protective sheath about the clamping body, requires that this operation be done separately from the assembly of the flat cable within the clockspring housing. Accordingly, an improved structure is desired which allows for the simple, inexpensive and quick attachment of external conductor wires to the electrical conductors of the flat cable so that all assembly of the clockspring may occur prior to the attachment of the external cables.
Generally, clocksprings have been known to have been assembled having at least three components. U.S. Pat. No. 4,607,898, describes a clockspring having a first half and a second half which is a assembled by a face plate. The assembly of the clockspring having three or more parts is disadvantageous due to the need to manufacture and then assemble the multiple parts which is costly and time-consuming and the increased number of bearing surfaces which create noise. Accordingly, there is desired a clockspring which has only two parts and a single bearing surface and may be assembled together quickly and easily. Such an assembly including all of the above described advantages is possible by incorporating the structures of the present invention either in a single clockspring assembly or as individual components of separate clockspring assemblies.
It is an object of the present invention to overcome all of the disadvantages of the prior art clocksprings by incorporating a clockspring structure which provides a design which is quickly and inexpensively assembled.
It is another object of the present invention to provide a clockspring assembly which is immobile until it is attached to a standard steering column.
It is a further object of this invention to provide a clockspring assembly that becomes immobile once it is disengaged from a standard steering column shaft.
It is yet another object of this invention to provide a clockspring assembly which remains immobile after assembly to a steering column but after adjustments to the steering column are made and without disassembling the clockspring from within a steering housing and steering wheel, the clockspring may be mobilized.
It is a further object of the present invention to provide a two-piece clockspring which may be assembled quickly and easily.
It is another object of the present invention to provide a clockspring structure which allows for the complete assembly of the clockspring prior to attachment of external cables.
It is yet another object of the present invention to provide for a clockspring assembly which allows for the quick and easy attachment of external cables at the conclusion of the assembly of the clockspring itself.